Micro-Electro-Mechanical System (MEMS) devices may be used in various applications such as micro-phones, accelerometers, inkjet printers, etc. A commonly used type of MEMS devices includes a capacitive sensor, which utilizes a movable element as a capacitor plate, and a fixed element as the other capacitor plate. The movement of the movable element causes the change in the capacitance of the capacitor. The change in the capacitance may be converted into the change in an electrical signal, and hence the MEMS device may be used as a microphone, an accelerometer, or the like.